C语言 GCC linaro 编译器抛出错误“未知类型名称 size_t”

GCC linaro compiler throws error "unknown type name size_t"

提问by rashok

I am using GCC Linarocompiler for compiling my code. Its throwing the error unknown type name size_tfrom libio.h. Its included from stdio.h. In my code I am just including stdio.h.

我正在使用GCC Linaro编译器来编译我的代码。它unknown type name size_t从libio.h. 它包括从stdio.h. 在我的代码中，我只包括stdio.h.

Can any one please how to resolve this error.

任何人都可以请如何解决此错误。

回答by Andrew Piroli

As per C99, §7.17, size_tis not a builtin type but defined in <stddef.h>.

根据 C99，第 7.17 节，size_t不是内置类型，而是在<stddef.h>.

Including the <stddef.h>header should fix your problem.

包含<stddef.h>标题应该可以解决您的问题。

回答by yano

For what it's worth, I had this exact same problem with a QT project, where I was using a Linaro compiler to (on both x86 Windows and x86 Linux) build for ARM Linux. Using the exact same code and .pro file, I had no problems building on Windows, but I had a litany of errors building on the Linux box, beginning with the unknown type name 'size_t'in libio.hwhich traced back to a #include <stdio.h>. I looked in the stdio.h(in the sysroot for the target hardware, not on the host machine), and a few lines down was #include <stddef.h>(much before #include <libio.h>), so stddef.hwas definitely getting included. However, upon further inspection, stddef.hwas completely empty with a file size of 1 byte. This was true for stddef.hin my sysroot and on my host machine. I have no idea why these files were empty.

值得一提的是，我在 QT 项目中遇到了完全相同的问题，我使用 Linaro 编译器（在 x86 Windows 和 x86 Linux 上）为 ARM Linux 构建。使用完全相同的代码和.pro文件，我没有问题，建立在Windows，但我有错误，构建在Linux中一连串的，与开始unknown type name 'size_t'在libio.h其中追溯到#include <stdio.h>。我查看了stdio.h（在目标硬件的 sysroot 中，而不是在主机上），下面几行是#include <stddef.h>（很早以前#include <libio.h>），所以stddef.h肯定被包括在内。但是，经过进一步检查，stddef.h文件大小为 1 个字节，完全为空。stddef.h在我的 sysroot 和我的主机上都是如此。我不知道为什么这些文件是空的。

Anyway, turns out I had an extraneous INCLUDEPATH += /usr/include/linuxin my .pro file. On my Linux build machine, this added -I/usr/include/linuxto the Makefile generated by qmake. On my Windows build machine, this added -isystem /usr/include/linuxto the Makefile generated by qmake. Once I commented this out, these lines were removed from the Makefiles and it built right up on both build machines. -isystem /usr/include/linuxapparently never caused any trouble on the Windows build machine, so there was no harm in removing INCLUDEPATH += /usr/include/linux.

无论如何，事实证明我的INCLUDEPATH += /usr/include/linux.pro 文件中有一个无关紧要的文件。在我的 Linux 构建机器上，这将添加-I/usr/include/linux到 qmake 生成的 Makefile 中。在我的 Windows 构建机器上，这已添加-isystem /usr/include/linux到 qmake 生成的 Makefile 中。一旦我将其注释掉，这些行就从 Makefile 中删除了，并且它在两台构建机器上都建立起来了。 -isystem /usr/include/linux显然从未在 Windows 构建机器上造成任何问题，因此删除INCLUDEPATH += /usr/include/linux.

I don't really know why this fixed my problem, but I suspect it was some kind of conflict between header files. Perhaps it was mixing host header files with sysroot header files, or creating a circular dependency somehow. GCC documentation says that anything included with the -Ioption will take precedence over a system header file. My best advice for this problem is to take a hard look at exactly which header files are being included and where they are coming from.

我真的不知道为什么这解决了我的问题，但我怀疑这是头文件之间的某种冲突。也许是将主机头文件与 sysroot 头文件混合在一起，或者以某种方式创建了循环依赖。GCC 文档说该-I选项中包含的任何内容都将优先于系统头文件。对于这个问题，我最好的建议是仔细查看包含哪些头文件以及它们来自哪里。

回答by Galaxy

Both stdio.hand stdlib.hinclude the data type size_t. They include this data type because the functions declared in these headers either take size_tas a parameter, or return it as a return type. size_titself is a typedefto an unsigned integral type and it's also returned by the sizeofoperator.

两者stdio.h并stdlib.h包括该数据类型size_t。它们包含此数据类型，因为在这些标头中声明的函数要么将其size_t作为参数，要么将其作为返回类型返回。size_t本身是一个typedef无符号整数类型，它也由sizeof运算符返回。

And because the sizeofoperator is built into the C Programming Language itself, not included via some library, then how can size_tbe an unknown type name?

并且因为sizeof操作符是内置在 C 编程语言本身中的，没有包含在某个库中，那么怎么会size_t是一个未知的类型名称呢？